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std::search_n - cppreference.com

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<metanoindex/>

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Elemento definito nell'header

<algorithm>

template< class ForwardIt, class Size, class T > ForwardIt1 search_n( ForwardIt first, ForwardIt last, Size count, const T& value );

 (1)

template< class ForwardIt, class Size, class T, class BinaryPredicate > ForwardIt1 search_n( ForwardIt first, ForwardIt last, Size count, const T& value, BinaryPredicate p );

 (2)

Ricerche la [first, last) gamma per la prima sequenza di conteggio elementi identici, ciascuno pari al valore determinato valore. La prima versione utilizza operator== di confrontare gli elementi, la seconda versione utilizza il predicato binario dato p.

Original:

Searches the range [first, last) for the first sequence of count identical elements, each equal to the given value value. The first version uses operator== to compare the elements, the second version uses the given binary predicate p.

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Parametri

first, last -

la gamma di elementi da esaminare

Original:

the range of elements to examine

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count -

la lunghezza della sequenza di ricerca

Original:

the length of the sequence to search for

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value -

il valore degli elementi da ricercare

Original:

the value of the elements to search for

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p - binary predicate which returns ​true if the elements should be treated as equal.

The signature of the predicate function should be equivalent to the following:

bool pred(const Type1 &a, const Type2 &b);

The signature does not need to have const &, but the function must not modify the objects passed to it.
The type Type1 must be such that an object of type ForwardIt can be dereferenced and then implicitly converted to Type1. The type Type2 must be such that an object of type T can be implicitly converted to Type2.

​

Type requirements
-ForwardIt must meet the requirements of ForwardIterator.

Valore di ritorno

Iiterator all'inizio della sequenza trovato [first, last) gamma. In assenza di tale sequenza viene trovato, viene restituito last.

Original:

Iiterator to the beginning of the found sequence in the range [first, last). If no such sequence is found, last is returned.

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Complessità

Alla maggior parte delle applicazioni last - first del predicato.

Original:

At most last - first applications of the predicate.

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Possibile implementazione

First version 
template<class ForwardIt, class Size, class T>
ForwardIt1 search_n(ForwardIt first, ForwardIt last,
                          Size count, const T& value)
{
    Size curr_count = 0;
    ForwardIt result, t_last = first;
    std::advance(t_last, std::distance(first, last) - count + 1);
 
    for (; first != t_last; first++) {
        curr_count = 0;
        result = first;
        while (*first == value) {
            curr_count++;
            if (curr_count == count) {
                return result;
            }
            ++first;
        }
    }
    return last;
}
Second version 
template<class ForwardIt, class Size, class T, class BinaryPredicate>
ForwardIt1 search_n(ForwardIt first, ForwardIt last,
                          Size count, const T& value, BinaryPredicate p)
{
    Size curr_count = 0;
    ForwardIt result, t_last = first;
    std::advance(t_last, std::distance(first, last) - count + 1);
 
    for (; first != t_last; first++) {
        curr_count = 0;
        result = first;
        while (p(*first == value)) {
            curr_count++;
            if (curr_count == count) {
                return result;
            }
            ++first;
        }
    }
    return last;
}

Esempio

Vedi anche

trova l'ultima sequenza di elementi di un certo intervallo

Original:

finds the last sequence of elements in a certain range

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(funzione di modello) [modifica]

trova il primo elemento che soddisfi i criteri specifici

Original:

finds the first element satisfying specific criteria

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(funzione di modello) [modifica]
searches for a range of elements
(funzione di modello) [modifica]